Neurosecretion is the complex process by which the sub-set of neurons that produce peptides as their chemical messages synthesize, process, transport, store, and release their specific products. Neuropeptides have been shown to be involved in coordination of endocrine function, regulation of salt and water balance, control of pain, appetite, sleep cycles, and memory. The proposed studies are intended to elucidate mechanisms of molecular regulation of the various stages of the neurosecretory process. The caudal neurosecretory complex (CNC), found in the posterior portion of the spinal cord of teleost fish, can be maintained in organ culture for several days, under which conditions quantitative measurements of various stages of the neurosecretory process can be made. The CNC of the goby, Gillichthys mirabilis, is used as a model system in which to carry out the proposed work. The CNC produces at least two biologically active peptides, Urotensin I (UI) and Urotensin II (UII) which are structurally and functionally related to mammalian corticotropin releasing factor and somatostatin, respectively. The proposed work will use a combination of in vivo and organ culture studies to define the physiological regulators of UI and UII release, infer the amino acid sequence of their preprohormones from the nucleotide sequences of cloned cDNA, sequence the genes encoding UI and UII, and study the coordination of transcription, translation, and processing with stimulus-specific release of neuropeptide.